• Journal of the Korean Society for Precision Engineering
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• v.24 no.3 s.192
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• pp.47-54
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• 2007

This paper describes the development of the intelligent gripper with two 3-axis force sensor that can measure forces Fx, Fy, Fz simultaneously, for stably grasping an unknown object. In order to grasp an unknown object using an intelligent gripper softly, it should measure the force in the gripping direction and the force in the gravity direction, and perform the force control using the measured farces. Thus, the intelligent gripper should be composed of 3-axis force sensor that can measure forces Fx, Fy, Fz at the same time. In this paper, the intelligent gripper with two 3-axis force sensor was manufactured and its characteristic test was carried out. The fabricated gripper could grasp an unknown object stably. Also, the sensing element of 3-axis force sensor was modeled and designed with five parallel-plate beams, and 3-axis force sensor for the intelligent gripper was fabricated. The characteristic test of the made sensor was carried out.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2821-2829
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• 2011

Since the KTX was in operation in 2004, a number of researches on increasing the train speed have been conducted. Currently, the Honam High-speed train system is designed for the operation velocity of 350km/h. The societal demand expects higher operation speed, whereas the existing construction method and design specification are questioned in the KTX operation in the velocity over 350 km/h. In this study, a full-scale model test was conducted to obtain the preliminary data that is necessary to understand deformation characteristics of the reinforced road bed and the subgrade layers. In the full-scale model test, direct arrival seismic tests, crosshole seimic test, in-situ bender element test and sensing bar test were employed to measure the stiffness and deformation of the trackbed. The systematic analysis on the different set of measurements enhances the understanding of the behavior of the trackbed.

• Smart Structures and Systems
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• v.8 no.3
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• pp.275-302
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• 2011

This is a review paper on mathematical modeling of actively controlled piezo smart structures. Paper has four sections to discuss the techniques to: (i) write the equations of motion (ii) implement sensor-actuator design (iii) model real life environmental effects and, (iv) control structural vibrations. In section (i), methods of writing equations of motion using equilibrium relations, Hamilton's principle, finite element technique and modal testing are discussed. In section (ii), self-sensing actuators, extension-bending actuators, shear actuators and modal sensors/actuators are discussed. In section (iii), modeling of thermal, hygro and other non-linear effects is discussed. Finally in section (iv), various vibration control techniques and useful software are mentioned. This review has two objectives: (i) practicing engineers can pick the most suitable philosophy for their end application and, (ii) researchers can come to know how the field has evolved, how it can be extended to real life structures and what the potential gaps in the literature are.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.429-435
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• 2015

This study proposes a re-adhesion algorithm that has stable traction effort for rolling stock slip/slide minimization when deliverable traction decreases by slip. The proposed scheme estimates appropriate reference speed using two encoders for reducing slip and controls traction effort stably and has stable control characteristics for disturbance. The algorithm which uses the maximum adhesive effort by instantaneous estimation of adhesion force stably controls traction effort and gives rolling stock excellent acceleration and deceleration characteristics. And a slip sensing element that can quickly detect slip is used. Load motor and inverter were checked in various slip conditions for creating various line conditions.

• Transactions on Control, Automation and Systems Engineering
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• v.2 no.1
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• pp.62-68
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• 2000

Fixtures are used in almost all phases of machining and assembly to position and hold a part accurately. The class of fixture which consists of 3 locators and 1 clamp(3L/1C) is known as the minimal set that can provide form closure which is a kinematic constraint condition for preventing all planar motions. This type of fixtures has advantages in terms of the number of fixture elements required, the time for clamping, and so on. However it is not widely used in industry because reliable loading scheme has not been reported. In this paper, we propose a method to load the class of 3L/1C fixtures using compliant motions. The planner is developed for synthesizing compliant motions to achieve precise final fixture configuration in the presence of sensing and control uncertainties. A novel approach to eliminate uncertainty in part orientation by adding one extra fixture element called an aligning pin is proposed.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.137-140
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• 2003

Shorted-turns can have significant effects on a generator and its performance. Shorted-turn sensor for synchronous generator's field winding have been developed. One of effective method detecting inter-turn short circuits on round rotor winding is a method using sensor detecting. But the method needs duplicate design of sensor for characteristic change according to types and forms of generator Thus sensing skill without sensor depend on change of electric property in generator. For the reason, this paper presents shorted-turns phenomenon and the characteristic analysis of shorted-turns In synchronous generator by using 2-D finite element method(FEM).

• Journal of electromagnetic engineering and science
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• v.12 no.1
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• pp.37-44
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• 2012

This paper describes a compact and novel wireless vital sign sensor at 2.4 GHz that can detect heartbeat and respiration signals. The oscillator circuit incorporates a planar resonator, which functions as a series feedback element as well as a near-field radiator. The periodic movement of a human body during aerobic exercise could cause an input impedance variation of the radiator within near-field range. This variation results in a corresponding change in the oscillation frequency and this change has been utilized for the sensing of human vital signs. In addition, a surface acoustic wave (SAW) filter and power detector have been used to increase the system sensitivity and to transform the frequency variation into a voltage waveform. The experimental results show that the proposed sensor placed 20 mm away from a human body can detect the vital signs very accurately.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.209-212
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• 1991

Recently, oxide semiconductor gas sensors consisted of n-type semiconductor materials such as $SnO_2$, ZnO and $Fe_2O_3$ have been widely used to detect reducing gases. The advantage of thick-film technology include the possibility of mass-production and automation, that of integrating the sensing element in a hybrid circuit and that of fuctional trimming of the sensor and/or the circuit. which would enable really interchangeable transducers to be prepared. In this paper, we made ZnO and $SnO_2$ gas sensors and investigated the sensitivity to CO gas. Therefore, we compared a ZnO gas sensor with a $SnO_2$ gas sensor.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.479-482
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• 2004

Laminate Design of a composite tube for a space telescope(Fig. 1) under hygrothermal load is studied. Carpet plots for laminate effective engineering constants are generated and used for selecting the best tube lay-ups satisfying the optomechanical requirements for a space telescope being dimensional1y stable under orbital thermal loading. Despace of the tubes constructed with the selected lay-ups are calculated with a Zig-Zag Triangular Element which accurately represents through thickness stress variations for laminated structures. The effects of moisture absorption when exposed to humidity environment and moisture desorption through outgassing on the dimensional stability are also investigated.

• Proceedings of the KSRS Conference
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• v.2
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• pp.764-767
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• 2006

It can be important framework data to monitor the change of land-use pattern of river boundary in design and management of river. This study analyzed the change of land-use pattern of Gab- and Yudeung River using time-series aerial images. To do this, we carried out radiation and geometric correction of image, and estimated land-use changes in inland and floodplain. As the analysis of inland, the ratio of residential, commercial, industrial, educational and public area, that is urbanized element, increases, but that of agricultural area shows a decline on the basis of 1990. Also, Minimum Distance Method, which is a kind of supervised classification method, is applied to extract water-body and sand bar layer in floodplain. As the analysis of land-use, the ratio of level-upped riverside land and water-body increases, but that of sand bar decreases. These time-series land use information can be important decision making data to evaluate the urbanization of river boundary, and especially it gives us goodness in river development project such as the composition of ecological habitat.